Identification of specific transducin alpha subunits in retinal rod and cone photoreceptors

Transducin is a guanyl nucleotide-binding protein that couples rhodopsin photolysis to hydrolysis of guanosine 3',5'-monophosphate in rod photoreceptor cells of vertebrate retinas. Several complementary DNA clones encoding transducin subunits have recently been characterized. One clone, isolated from a bovine retina complementary DNA library, encodes a previously unidentified polypeptide with an amino acid sequence 78% identical to the sequence of the alpha subunit of bovine rod outer segment transducin. Antibodies to a synthetic peptide with amino acid sequence derived specifically from this novel polypeptide recognize a 41-kilodalton polypeptide in homogenates of bovine retina. Localization of this polypeptide in bovine retina by indirect immunofluorescence demonstrates that it is expressed only in cone outer segments. Antibodies to specific sequences found only in the rod transducin alpha subunit recognize a polypeptide localized only in the rod outer segment. Therefore, bovine rod and cone cells each express structurally related yet significantly different forms of transducin.     

Evidence for absence of equine arteritis virus in the horse population of New Zealand

AIM: To summarise investigation and laboratory data collected between 2001 and 2011 to provide evidence that equine arteritis virus is not present in the horse population of New Zealand.

METHODS: Analysis was carried out on results from laboratory tests carried out at the Ministry for Primary Industries Animal Health Laboratory (AHL) for equine arteritis virus from horses tested prior to being imported or exported, testing of stallions as part of the New Zealand equine viral arteritis (EVA) control scheme and testing as part of transboundary animal disease (TAD) investigations for exclusion of EVA. Horse breeds were categorised as Thoroughbred, Standardbred or other.

RESULTS: A total of 7,157 EVA serological test records (from import and export testing, EVA control scheme testing and TAD investigations) were available for analysis between 2005 and 2011. For the three breed categories a seroprevalence of ≤1.6% at the 95% confidence level was determined for each category. Between 2001 and 2011, as part of the EVA control scheme, the EVA status of 465 stallions was determined to be negative. During 2005–2011 EVA was excluded from 84 TAD investigations.

CONCLUSIONS: There was no evidence of equine arteritis virus being present in the general horse population outside of carrier stallions managed under the EVA control scheme.

CLINICAL RELEVANCE: Equine arteritis virus is absent from the general horse population of New Zealand.     

Effects of Gonadotropins on In Vitro Maturation and of Electrical Stimulation on Parthenogenesis of Canine Oocytes

The objective of this study was to determine the effects of gonadotropins on in vitro maturation (IVM) and electrical stimulation on the parthenogenesis of canine oocytes. In experiment I, cumulus oocyte complexes were collected from ovaries at a random phase of the oestrus cycle and cultured on maturation medium treated with hCG or eCG for 48 or 72 h. There were no significant differences in the effects on the metaphase II (MII) rate between the hCG and eCG treatment groups over 48 h (5.4% vs 5.5%). The MII rate in the co-treatment group of hCG and eCG for 48 h was higher than in each hormone treated group (15.5%, p < 0.05). In experiment 2, the parthenogenetic effect on oocyte development, at various electrical field strengths (1.0, 1.5, 2.0 kV/cm DC) for 60 or 80 μs with a single DC pulse after IVM on the co-treatment of hCG and eCG, was examined. The rate of pronuclear formation (37.1%) in electrical activation at 1.5 kV/60 μs without cytochalasin B (CB) was higher than that of oocytes activated in the other groups (p < 0.05). However, we did not observe the cleavage stages. Also, CB did not influence parthenogenesis of canine oocytes. The results showed that the pronucleus formation rate, indicative of the parthenogenesis start point, could be increased by electrical stimulation. Therefore, these results can provide important data for the parthenogenesis of canine oocytes and suggest the probability of parthenogenesis in canines.     

Root lesions in large loblolly pine (Pinus taeda L.) following inoculation with four root‐inhabiting ophiostomatoid fungi

Loblolly pine decline, characterized by deteriorating root systems leading to shortening and thinning of foliage, has been observed throughout portions of the south‐eastern United States. Several root‐inhabiting ophiostomatoid fungi, including Leptographium procerum, Leptographium terebrantis, Leptographium serpens, and Grosmannia huntii are associated with lateral root damage on declining loblolly pine. Trees of various ages were inoculated in primary lateral roots during fall (2006 and 2007) and spring (2007 and 2008). All fungi caused a darkened, resin‐filled lesion on the surface of the phloem, extending into the xylem that was larger than that of controls. Only lesions associated with G. huntii infection were significantly larger in the spring season, compared with the fall. Grosmannia huntii was found to be the most virulent fungus, causing lesions that were longer, deeper and larger than all other fungal species during the spring and larger than L. terebrantis and L. procerum in the fall. Leptographium serpens was the second most virulent fungal species, causing lesions larger than L. procerum and L. terebrantis (with the exception of lesion depth) during both seasons. These tests indicate that G. huntii and L. serpens are significant root pathogens, capable of causing considerable damage, while L. terebrantis and L. procerum may be less virulent. Depending on the actions of their vectors, G. huntii and L. serpens may be responsible for significant root deterioration and tree disease.     

Dogs on the catwalk: Modelling re-introduction and translocation of endangered wild dogs in South Africa

In South Africa, a plan was launched to manage separate sub-populations of endangered African wild dogs (Lycaon pictus) in several small, geographically isolated conservation areas as a single meta-population. This intensive management approach involves the re-introduction of wild dogs into suitable conservation areas and periodic translocations among them. Despite the initial failures and high costs associated with wild dog re-introductions and translocations, there is no predictive framework available to quantify which management protocol is the most efficient. We therefore developed an individual-based model of wild dog population and pack dynamics, which accounts for the wild dogs’ social complexity. The model appeared to capture the essential characteristics of a real wild dog population from Hluhluwe-iMfolozi Park, South Africa and to be relatively robust to parameter uncertainty, suggesting that the model is valid enough for addressing management problems. The model enabled us to quantify a critical initial number of packs (two) and individuals per pack (six) necessary for a re-introduced wild dog population to establish itself in the release area. We also found a practically feasible intervention regime at which a re-introduced wild dog population had the best chance of persistence: intermittently adding packs (at least every 6 years) and harvesting disperser groups (as often as every 4 years) for translocation to other release sites, without threatening the small source population. This study demonstrates that individual-based models can be a powerful decision-support tool in re-introduction planning and provides insight into how populations made up of social groups have dynamics, and ultimately persistence, determined by individual behaviour.     

Differential expression of insulin‐like growth factor family members in immature cumulus–oocyte complexes from dairy cows with different genotypes

It has been evident the improvement of in vitro embryo production (IVEP) in dairy cows. Nevertheless, it is known that differences in the number and quality of oocytes between taurine and zebu females impact the efficiency and economic viability of IVEP. As the insulin‐like growth factor (IGF) system is related to follicular and oocyte development, we aimed to quantify mRNA abundance of IGF system members and pregnancy‐associated plasma protein‐A (PAPPA) in the cumulus–oocyte complexes (COCs) of Gir, 1/2 Holstein × 1/2 Gir and Holstein cows. Four pools of 30 immature COCs from Gir, 1/2 Holstein × 1/2 Gir and Holstein cows were obtained by ovum pickup (OPU), and the oocytes and cumulus cells (CC) were mechanically separated and stored at ?80°C. Total RNA was extracted from pools of 30 oocytes and their respective CC. Expression of target genes was assessed by real‐time RT‐PCR. In oocytes, the abundance of IGFR1 mRNA was higher (p < .05) in Gir cows compared with the other breeds. In contrast, in CC, mRNA encoding IGF2 (p < .05), IGFR2 (p < .05) and IGFBP4 (p < .01) was higher in Holstein donors compared with Gir and 1/2 Holstein × 1/2 Gir cows. Additionally, the abundance of PAPPA mRNA was higher in oocytes (p < .001) and CC (p < .01) in Gir and 1/2 Holstein × 1/2 Gir cows compared with the Holstein donors. In conclusion, the higher abundance of PAPPA mRNA in the oocytes and CC from Gir and cross‐breed donors combined with the low expression of IGFBP4 in the CC suggests an enhancement of the bioavailability of IGF‐free when compared with Holstein COCs.